[7.x] update beats for bumping version to 7.9

[simitt]

Motivation/summary

Update beats framework, which includes a version update to 7.9

Checklist

- [ ] I have signed the Contributor License Agreement.
- [ ] I have updated CHANGELOG.asciidoc

I have considered changes for:

• documentation
• logging (add log lines, choose appropriate log selector, etc.)
• metrics and monitoring (create issue for Kibana team to add metrics to visualizations, e.g. Kibana#44001)
• automated tests (add tests for the code changes, all unit tests pass locally)
• telemetry
• Elasticsearch Service (https://cloud.elastic.co)
• Elastic Cloud Enterprise (https://www.elastic.co/products/ece)
• Elastic Cloud on Kubernetes (https://www.elastic.co/elastic-cloud-kubernetes)

How to test these changes

make test

[apmmachine]

💚 Build Succeeded

Expand to view the summary

Build stats

• Build Cause: [Pull request [7.x] update beats for bumping version to 7.9 #3770 opened]

• Start Time: 2020-05-07T11:12:03.749+0000

• Duration: 26 min 18 sec (1578301)

• Commit: 0480ce9

Test stats 🧪

Test	Results
Failed	0
Passed	3008
Skipped	142
Total	3150